Coarse-Grained Simulations of Rapid Assembly Kinetics for Polystyrene-b-poly(ethylene oxide) Copolymers in Aqueous Solutions
Coarse-Grained Simulations of Rapid Assembly Kinetics for Polystyrene-b-poly(ethylene oxide) Copolymers in Aqueous Solutions
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DOI：
10.1021/jp805826a
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发表时间：
2008-12-25
影响因子：
3.3
通讯作者：
Panagiotopoulos, Athanassios Z.
中科院分区：
文献类型：
--
作者：
Chen, Ting;Hynninen, Antti-Pekka;Panagiotopoulos, Athanassios Z.
本文提出了一个聚苯乙烯-聚环氧乙烷嵌段共聚物水溶液的粗粒度隐式溶剂模型，并利用布朗动力学模拟研究了其组装动力学。该聚合物被建模为一个链的自由连接的珠子通过有效的潜力相互作用。粗粒力场参数由实验热力学量，包括回转半径，第二维里系数，聚集数和临界胶束浓度相匹配。我们调查的冷却速率（类似于快速沉淀中的溶剂质量变化率），聚合物浓度和摩擦系数的组装动力学的影响，并比较模拟结果的闪光纳米沉淀实验。我们发现，当摩擦系数大于1时，组装动力学与摩擦系数的倒数呈线性标度关系。当冷却时间小于特征胶束化时间时，得到稳定的动力学被捕集;否则，形成接近平衡的胶束。特征胶束化时间估计仅为3-6 ms，与先前在实验中确定的30-40 ms相反。我们建议，以前的实验探讨胶束簇的形成，而在这项工作中的模拟研究了从自由聚合物链组装的单个胶束的动力学。
We present a coarse-grained, implicit solvent model for polystyrene-b-poly(ethylene oxide) in aqueous solution and Study its assembly kinetics using Brownian dynamics Simulations. The polymer is modeled as a chain of freely jointed beads interacting through effective potentials. Coarse-grained force field parameters are determined by matching experimental thermodynamic quantities including radius of gyration, second virial coefficient, aggregation number, and critical micelle concentration. We investigate the influence of cooling rate (analogous to the rate of solvent quality change in rapid precipitations), polymer concentration, and friction coefficient on the assembly kinetics and compare simulation results to flash nanoprecipitation experiments. We find that assembly kinetics show a linear scaling relation with inverse friction coefficient when the friction coefficient is larger than 1. When the cooling time is less than the characteristic micellization time, stable kinetically arrested clusters are obtained; otherwise, close-to-equilibrium micelles are formed. The characteristic micellization time is estimated to be only 3-6 ms, in contrast to 30-40 ms previously determined in experiments. We suggest that previous experiments probed the formation of micellar clusters while simulations in this work studied the kinetics of a single micelle assembled from free polymer chains.